Method of treating vinegar



Patented Nov. 21, 1950 METHOD OF TREATING VINEGAR Rolland F. Cohee, Jr.,Wheaton, Ill., assignor to Corn Products Refining Company, New York, N.Y., a corporation of New Jersey No Drawing.

Application February 8,1950,

Serial No. 143,160

16 Claims.

This invention relates to the removal of metallic ions from vinegar.More particularly, it relates to the removal of traces of metallic ionssuch as iron, copper and lead from vinegar.

The presence of trace metals, such as iron and copper and the like, invinegar is objectionable because they cause a haze in the vinegar, areresponsible for discoloration and on standing may precipitate or settleout. Several methodshave been proposed for the removal of traces ofmetallic ions from vinegar. Clarification with gelatin and tannin hasnot been successful. Treatment with activated carbon removes only partof the iron but at the same time removes the color from "ciger vinegar.The use of ion exchange resins has also been proposed but this iscomplicated and expensive. I

It is an object of the present invention to provide a new and improvedmethod of removing trace metals and their eflfects from vinegar. Afurther object is to provide a method for the removal of trace metalsfrom vinegar which is simple and economical. Still a further object isto remove from cider vinegar the objectionable color due to trace metalswithout removing the natural color of the vinegar. Other objects willappear hereinafter.

I have discovered that trace metals present in vinegar in the form ofmetal salts may be removed therefrom by treating the vinegar with smallamounts of phytate salts. Among the phytate salts suitable for thispurpose are sodium phytate, potassium phytate, ammonium phytate,caleium'phytate, magnesium phytate, and the mixed salts of phytic acid,such as calcium-magnesium phytate, or mixtures thereof. Phytic acid isalso suitable for carrying out the invention. Mixed salts of phytic acidmay be obtained by precipitation from acidic plant extracts, as, forexample, corn steep liquor, with an alkaline substance such as, forexample, calcium hydroxide, lime or magnesium hydroxide. When corn steepliquor or similar acidic extracts of plant materials are neutralizedwith calcium hydroxide, or lime, or magnesium hydroxide, theprecipitates that form are crude salts of phytic acid, comprisingessentially calcium phytate, or magnesium phytate, or mixtures thereof.If calcium hydroxide, or lime, is used as the precipitant, theprecipitate consists mainly of calcium phytate but since plant extractsalways contain some magnesium, some of this will beretained in theprecipitate. Such precipitate will usually contain five calcium atoms toone magnesium atom. If magnesium 2 hydroxide is used as a precipitant,the precipitate consists almost entirely of magnesium phytate but asmall amount of calcium may be contained therein. These precipitatesshould be purified of proteinaceous materials contained in the steepliquor. The term mixed calciummagnesium phytate, as used hereinafter, isintended to include all mixed calcium-magnesium salts of phytic acidregardless of which metal predominates.

The amount of'phytate salt or phytic acid which may be used, inaccordance with the present invention, may vary rather widely. Ifcomplete removal of trace metals is desired, the amount to be addedshould be sufiicient to react with all the metal salts present in thevinegar to form insoluble phytate complexes. Amounts in excess of thisare not ordinarily detrimental nor are they necessary, except ashereinafter specified. Ordinarily, 0.1 to 1.0 g. of each substancespecified per liter of vinegar is suificient. The insoluble phytatecomplex may be removed from the vinegar easily as by filtration.

The phytate salt or phytic acid to be added to the vinegar may be addedin aqueous solution or directly, the specified materials to be added allbeing somewhat soluble in vinegar.

After the phytate salt or phytic acid is added, the vinegar may beheated to about F., or preferably to about F., or higher (particularlywhen calcium or mixed calcium-magnesium phytate is used) to effectprecipitation or insolubilization of the phytate complex and tofacilitate flocculation thereof.

The precipitates will flocculate at room temperature but the amount oftime required is considerabl longer than when the vinegar has beenheated. Generally, a period of 21 days, at room temperature, issufilcient.

Heating also serves an additional purpose when calcium phytate or mixedcalcium-magnesium phytate is used as the additive. These phytates aresoluble in vinegar (5 g./liter of 5 percent acetic acid or 50 graincider vinegar) at low temperatures but above about 160 F., a haze forms,and at higher temperatures, including the boiling temperature, bothsalts separate out as flocculant precipitates. Substantially all of theexcess of calcium or mixed calcium-magnesium phytate present in thevinegar, if an excess has been added, may be removed by heating andfiltering the vinegar at temperatures above 160 F. The precipitatedinsoluble phytate complexes with the iron, lead, copper,

vinegar, temperatures above about 160 F. should preferably be avoided toprevent dissolved phytates from precipitating out. While pure calciumphytate will be redissolved when the vinegar is cooled, commercial ortechnical grades will not redissolve completely.

More efiicient removal of metals is effected by adding the phytate orphytic acid in two or more doses, the total amount being slightly morethan the theoretical, carrying out heat treatment or allowing a periodfor the formation and flocculation of the insoluble precipitate andpreferably removing such precipitate, after the addition of each dose.If heat treatment is used, the vinegar should be cooled andfilteredbefore another dose is added.

It has been found that the addition of calcium phytate or mixedcalcium-magnesium phytate to cider vinegar has a tendency to reduce theamount of natural color, particularly when an excess of either of thesephytates is added. Apparently, the insoluble fiocculant phytateprecipitent. Table shows the percentage of removal of iron at differenttime intervals.

Table I Sample Number A B C Iron before treatment p. p. in 25 25 5 Daysafter treatment p. p. m 12 7 12 Percent iron removed 52 72 52 14 Daysafter treatme p. p. m 3 4 3 Percent iron removed 88 84 88 33 Days aftertreatment.-- p. p. m.. 2. 5 2. 5 2. 5 Percent iron removed 90 90 00EXAMPLE II A mixed calcium-magnesium phytate, as specitied in Example I,was added to two types of vinegar at the rate shown in Table II. TheVinegars were heated to 180 F. and then allowed to cool to roomtemperature and to stand for various times. The filtrates were analyzedfor iron and copper contents. The filtrates after standing several days,were filtered again and the new filtrates analyzed for iron and coppercontents.

EXAMPLE III A badly contaminated white distilled vinegar was treatedwith successive portions of mixed calcium-magnesium phytate (obtainedfrom steepwater, as in Example I) at the rate of 0.1g. 01 phytate per100 cc. of vinegar. The treated vinegar was heated to 180 F. after each.dose and filtered after standing for 15 minutes. The

tate adsorbs some of the natural coloring matter 35 vinegar was analyzedbefore and after treatment in the vinegar, 1. e., tannin. This tendencymay for iron and copper contents.

Table II white Cider Vinegar Distilled Date vmegar Samplel Date Sample2Date Bample3 Date Sample4 Date Gr. Ca-Mg phytate added per pint (450cc.) 0.01 0.02 0.10 0.0a 0.7 Iron before treatment, p. p. m.. 4 8/25 98/25 40 8/10 8/25 25 7/23 Iron after treatment, p. p. m. 2.5 8 26 4 SIE5 8/17 12.5 8 26 2.5 8 23 Iron after treatment, p. p. m g 6?; Copperbefore treatment, p.

p. m 1.5 8/25 10 .s/25 8/25 35 7/23 Copper after treatment, p.

p. m 1.25 8/26 4 8 28 25 8/26 a 8/25 Copper after treatment, p.

be decreased by adding only the theoretical amount of phytate to reactwith the metals as present. Color may be redeveloped by heating butTable temperatures above 160 F. should preferably be avoided for thereasons heretofore indicated.

- ite Vinegar By way of illustrating my invention, the follow- TreatmentDate Visual ing specific examples are provided; however, it Fe Cu is tobe understood that these examples are illustrative only and are notintended as limiting the v p p None, start 8/26/49 F0 invention to theseor any other particular ex o lg caphymelmcc 8/26/49 Heavy 12 3O amples.heat; let stand 15 min. ppt.

EXAM-P 2n l l b h t te/OO /26/4 d .g. ap ya 1 8 9 o 3 LE I '00 heat; legstand 15 25 mlll. Oli! A mixed calcium-magnesium phytate obtained 3rd0.lg. Ca phytate/100 8/28/49 Ppt 1 20 by precipitation with lime from cornsteep liquor 5, 75.5 and purified of proteinaceous impurities was addedto cider vinegar at the rate of 1.25 lbs. per 1000 gals. of vinegar. Thevinegar was then allowed to stand at room temperature for several weeks.Samples were withdrawn after five and 14 days, filtered, and analyzedfor iron condoubt due to the fact that copper phytate is more soluble invinegar than iron phytate.

EXAMPLE IV Vinegar was treated with severalamounts of both sodiumphytate and mixed calcium-magnesium phytate. After the addition of thesodium. or mixed calcium-magnesium phytate, the samples were heated .to180 F., allowed to cool and permit the precipitates to flocculate andsettie. The precipitates were collected by filtration and analyzed foriron and copper contents. Alter the filtrate had stood for a week, itwas again subjected to the above procedure. The analysis of ashedresidues indicates that the iron and copper were being removed in theprecipitates. The results of the. test are shown in Table IV. Thisexample also shows thatan excess of phytate material is not necessary toremove trace metals from vinegar.

2. Theprocess oi treating vinegar which com- .pr'ises adding thereto asuiiicient amount of phytate material to react with the metal saltspresent therein, heating the vinegar above about 160 F. to facilitateformation of insoluble phytate complexes and separating the insolublecomplexes from the vinegar, said phytate material added being selectedfrom the group consisting oi phytic acid and phytate salts soluble invinegar.

3. The process of removing trace metals from vinegar which comprisesadding thereto phytate Table IV Amount of Phytates Added to 450 cc.Vinegar, Grams Treatment Date Control Calcium Phytate Sodium PhytateHeat til 130 F. alter grams added. 7/23/49 0.0 0.0625 0.125 0.194 0.0625 0.125 0. 194 Grams of 1st precipitate 7/23/49 0. 0435 0. 0684 0.0773 0. 0408 0. 0642 0. 0612 Grams of 2nd precipitate 7/30/49 0. 03030.0248 0. 0356 0.0391 0.0317 0.0343 Grams of combined precipitates. 0.0798 0. 0932 0. 1129 0. 0794 0.0959 0. 0955 Iron after treatment, p. p.m 8/24/49 Untreatgg 2. 5 2. 6 2. 5 2. 5 2. 5 2. 5 Copper aftertreatment, p. p. m 8/28/49 Untreatgisi 3. 5 3. 6 3. 5 3. 5 3. 6 3. 5

EXAMPLE V consisting of phytic acid and phytate salts solu- This exampleshows the efiect of adding mixed calcium-magnesium phytate to fivepercent acetic acid solutions containing small amounts of lead andcopper. 0.06 gram of mixed calcium-magnesium phytate (from steepwater)was added to 100 cc. of five percent acetic acid solutions containingsmall amounts of lead and copper, as set forth in Table V. The solutionswere allowed to stand at room temperature 69 days. The results are givenin Table V.

Table V Date Blank 100 p. p. m. 50 p. p. m. 10 p. p. m.

0/l8/49 clean..- pptppt Clea 8124/49.... do p ppt ppt.

Date Blank p. p. m. 10 p. p. m. 5 p. p. 111.

6/18/49 Clear.. Clear Clear Clear 8/24/49 do ppt.... ppt... Do.

100 p. m. Pb, 10 p. p. 111. Pb. Date Blank l0 p. H]. Cu 5 p. p. m. Cu

6/18/49 Clear. ppt Clear. 8/24/49 do ppt. ppt.

I claim:

pierce.

" prises adding incrementally thereto mixed calcium-magnesium phytate atthe rate of 0.1 to 1.0 g. per liter of vinegar for 25 p. p. m. each ofiron and 35 p. p. m. of copper content, heating the vinegar to at leastF. after each addition, and thereafter separating the resultantinsoluble precipitate from the vinegar while the temperature of thevinegar is at least 160 F.

6. In the process of treating vinegar with a phytate materialselectedfrom the group consisting of phytic acid and phytate saltssoluble in vinegar, the. improvement which compr ses adding said phytatematerial incrementally, allowing insoluble phytate complex to form andremoving same after each addition of said phytate material.

7. The process of treating vinegar which comprises adding thereto sodiumphytate in amount to react with the metal salts present therein to forminsoluble phytate and removing said insoluble phytates from the vinegar.

8. The process of treating vinegar which comprises adding thereto asufficient amount of a phytate material to react with the metal saltspresent therein, heating the vinegar to about F. and separating theresultant insoluble complex from the vinegar, said phytate materialadded being selected from the group consisting of phytic acid, andphytate salts soluble in vine- 9. The process 01 treating vinegar whichcomprises adding thereto mixed calcium-magnesium phytate at the rate of0.1 to 1.0 g. per liter of vinegar, heating the vinegar to about-180 F.,andprises adding thereto a material selected from the group consistingof phytic acid and phytate-salts soluble in vinegar, thereafter heatingthe vinegar to at least about 180 F., cooling the vinegar to roomtemperature, and thereafter filtering the vinegar to remove insolublematerial therefrom.

'12. In the process of treating vinegar with a phytate material selectedfrom the group con-' sisting of phytic acid and a phytate salt solublein vinegar, the improvement which comprises adding the phytate materialincrementally and removing resultant insoluble material from thevinegar.

13. The process of treating vinegar which comprises adding theretocalcium phytate at the rate of 0.1 to 1.0 g. per liter of vinegar forparts p. p. m. each of iron and p. p. m. of copper content, heating thevinegar to at least F., and thereafter separating the resultantinsoluble precipitate from the vinegar while the temperature of thevinegar is at least 160 F.

14. The process of treating vinegar which comprises adding incrementallythereto calcium phytate at the rate of 0.1 to 1.0 g. per liter ofvinegar for 5 p. p. m. each of iron and 35 p. p. m. of copper content,heating the vinegar to at least 160 F'. after each addition, andthereafter separating the resultant insoluble precipitate from thevinegar while the temperature of the vinegar is at least 160 F.

'15. The process of treating vinegar which comprises adding theretocalcium phytate at the rate of 0.1 to 1.0 g. per liter of vinegar,heating the vinegar to about F., and thereafter separating the resultantinsoluble precipitate.

16. The process of treating vinegar which comprises adding incrementallythereto calcium phytate at the rateof 0.1 to 1.0 g. per liter ofvinegar, heating thevinegar to at least 180 F., after each addition, andseparating the resultan insoluble precipitate from the vinegar.

ROLL-AND F. COHEE,.JR.

No references cited.

1. THE METHOD OF IMPROVING VINEGAR WITH RESPECT TO COLOR AND STABILITYWHICH COMPRISES ADDING THERETO A MATERIAL SELECTED FROM THE GROUPCONSISTING OF PHYTIC ACID AND PHYTATE SALTS SOLUBLE IN VINEGAR, ANDTHEREAFTER FILTERING SAID TREATED VINEGAR TO REMOVE INSOLUBLE PHYTATECOMPLEXES.